Fuel discharge member, a burner, a premixing nozzle of a combustor, a combustor, a gas turbine, and a jet engine

ABSTRACT

This invention relates to a fuel discharge member which can reduce the amount of NOx exhaust. The fuel discharge member is fixed on a fuel supply conduit, and comprises: a main body having an internal space which communicates with a fuel passage in the fuel supply conduit, fuel discharge outlets which communicate with the internal space, and a trailing edge. The thickness of the trailing edge is no more than 5 mm, or a flow passage block ratio of the fuel discharge member is no more than 10% with respect to the cross-sectional area of the air flow passage in which the fuel discharge member is to be placed. Alternatively, the main body is a flat tube.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a fuel discharge member that ispreferably used to reduce the amount of NOx exhaust, and a burner, apremixing nozzle of a combustor, a combustor, a gas turbine and a jetengine, which are equipped with this fuel discharge member.

[0003] 2. Description of Related Art

[0004] A gas turbine and a jet engine each include a compressor, acombustor, and a turbine. The compressor and the turbine are connectedto each other by means of a main shaft. The combustor is connected to anoutlet of the compressor.

[0005] A working fluid gas is compressed by the compressor in order tosupply a high-pressure gas to the combustor. The high-pressure gas isheated to a predetermined turbine inlet temperature by the combustor inorder to supply a high-pressure and high-temperature gas to the turbine.The high-temperature and high-pressure gas is expanded in a cylinder ofthe turbine, as the high-temperature and high-pressure gas passesbetween a stator blade and a rotor blade disposed on the main shaft ofthe turbine. Thereby, the main shaft is rotated, so that a shaft outputis generated. Since a shaft output can be obtained, wherein theconsumption power of the compressor is excluded, the shaft output can beused as a driving source by connecting an electric power generator tothe main shaft at the opposite side of the turbine, for example.

[0006] The jet engine uses the output in the form of kinetic energy of ahigh-velocity jet to directly propel an aircraft.

[0007] The development of the gas turbine and the jet engine describedabove has been promoted in order to reduce the emissions of NOx and thelike, in view of recent environmental problems. Particularly, variousresearch and development related to combustors has been undertaken andis disclosed in Japanese Unexamined Patent Application, FirstPublication No. Hei 8-54119, No. Hei 10-318541, No. Sho 60-126521, No.Hei 8-21627, No. Hei 9-119639, No. Hei 4-283316, and Japanese ExaminedPatent Application, Second Publication No. Hei 6-84817, for example.

[0008] In Japanese Unexamined Patent Application, First Publication No.Hei 8-21627, a fuel nozzle, which is used during the entire operation ofa gas turbine to reduce emissions of air pollutants in exhaust gas ofthe gas turbine, is disclosed. In the following, the fuel nozzle isdescribed with reference to FIG. 11.

[0009] This fuel nozzle includes a housing 1 and a central tube 2, andan annular chamber 3 is formed between the housing 1 and the centraltube 2. Downstream of the central tube 2, an inner swirler 4 and anouter swirler 5 are disposed so as to be connected to the downstreamside of the annular chamber 3. Downstream of the inner swirler 4 and theouter swirler 5, a combustion area is provided.

[0010] In a diffusion combustion mode, when a fuel gas is supplied tothe inner swirler 4 from an aperture 2 a that is provided near the frontend of the central tube 2, a portion of the air, which is supplied tothe annular chamber 3, is mixed with the fuel gas by the inner swirler4, so that diffusion flames are maintained in a diffusion mixing cup 6disposed at the downstream side of the inner swirler 4. On the otherhand, the remaining air which is supplied to the annular chamber 3, isled to the outer swirler 5 after being separated from the air which issupplied to the inner swirler 4, by means of a splitter vane whichextends circumferentially to form the diffusion mixing cup 6. At theupstream portion of the annular chamber 3, a plurality of spokes 7protrude toward the inside of the annular chamber 3. In a premixingcombustion mode, the fuel gas is supplied to the annular chamber 3 fromapertures 7 a of the spokes 7, and is subsequently mixed with the airwhich is supplied to the annular chamber 3. At that time, the flowpassage of the fuel gas, which communicates with the aperture 2 a tosupply the fuel gas to the inner swirler 4, is shut, and thereby, theentire fuel gas is supplied to the spokes 7. In FIG. 11, a fuel source 6and a fuel gas passage switching valve 9 are also shown.

[0011] As described above, since the spokes 7 are disposed at theupstream side of the inner swirler 4 and the outer swirler 5, a fuel/airmixture in the premixing combustion mode is supplied to the innerswirler 4 and the outer swirler 5 from the annular chamber 3, and isaccelerated to a high-velocity swirl through an aerodynamic vane. Thishigh-velocity swirl prevents the flashback of combustion from thecombustion zone into the annular chamber 3. Therefore, the surface ofthe premixing flame is stabilized, and the entirety of air which issupplied from the compressor is used so as to be mixed with the fuel gaswhich is supplied from the spokes 7. Therefore, a lean fuel/air ratio inthe premixing combustion mode can be obtained, thereby reducing theamount of NOx exhaust in the mid to high-load operating range of theturbine.

[0012] However, in recent gas turbines and jet engines, the combustiontemperature in the combustor tends to be set at a high temperature toimprove the efficiency of the combustion. Even in the premixingcombustion mode described above, since the range of the concentrationdistribution of the premixed fuel is broad due to the reasons describedbelow, a rich zone, wherein the fuel concentration (fuel/air ratio) isgreater than 1, is generated, so that NOx is generated in a highconcentration in the rich zone. Thus, it is difficult to reduce theamount of NOx exhaust from the combustor.

[0013] Particularly, when the combustion temperature is raised to overapproximately 1600° C., it is known that the concentration of NOxcontained in the combustion gas is rapidly increased. Therefore, whenthe combustion temperature is set to become near 1600° C. in order toincrease the efficiency of the combustion, even if the range of theconcentration distribution of the fuel is relatively narrow, NOx may beeasily generated. Therefore, it is desired to make the concentration ofthe premixed fuel uniform in order to improve efficiency of the gasturbine and the jet engine, and to reduce the NOx exhaust at the sametime.

[0014] In the following, the reasons why the range of the concentrationdistribution of the fuel is broad in the premixing combustion mode aredescribed. In this case, the fuel gas is supplied from the apertures 7 aof the spokes 7 of which a comparatively large cross-sectional areaprotrudes into the air flow passage. Thereby, downstream of the spokes7, a negative pressure zone is generated in the flow direction of theair. Then, the air flow is engulfed by the negative pressure area, sothat swirls are generated in the negative pressure area. Due to thegeneration of swirls, the fuel gas can be circumferentially supplied fora short time from the apertures 7 a disposed perpendicular to the airflow passage, for example. That is, the fuel gas loses penetration forcethrough the air flow. Therefore, the concentration distribution of thefuel gas becomes circumferentially nonuniform.

[0015] Japanese Unexamined Patent Application, First Publication No. Hei8-21627, No. Hei 10-318541, and No. Hei 9-119639 disclose spokesprotruding in the air flow passage and a device that supplies a fuel gasfrom an aperture of a hollow pole, for example. However, theconcentration distribution cannot be made uniform according to theseprior art publications.

SUMMARY OF THE INVENTION

[0016] The present invention has been made to solve the problemsdescribed above. An object of the present invention is to provide a fueldischarge member, which can be operated with high effectiveness bysetting a high-temperature of the combustion, and to reduce the amountof NOx exhaust at the same time, and is provided with a burner, apremixing nozzle, a combustor, a gas turbine, and a jet engine.

[0017] In order to achieve the object described above, the presentinvention utilizes the following constitution.

[0018] A fuel discharge member according to the present inventionincludes a main body to be fixed on a fuel supply conduit. The fueldischarge member includes a main body which has an internal space thatcommunicates with a fuel passage in the fuel supply conduit, fueldischarge outlets which communicated with the internal space, and atrailing edge. The thickness of the trailing edge may be no more than 5mm, or a flow passage block ratio of the fuel discharge member may be nomore than 10% of the cross-sectional area of the air flow passage inwhich the fuel discharge member is to be placed.

[0019] By the use of this fuel discharge member, since the thickness ofthe trailing edge is thin enough such that the flow passage block ratioof the fuel discharge member is no more than 10%, the effective area ofthe air flow passage is enlarged, so that the generation of swirls issuppressed at the downstream side of the fuel discharge member withrespect to the air flow.

[0020] Alternatively, the main body of the fuel discharge member may bea flat tube. By the use of this fuel discharge member, since theprojected area of the main body in the air flow direction is decreased,the effective area of the air flow passage is increased, so that thegeneration of swirls is suppressed at the downstream side of the fueldischarge member with respect to the air flow.

[0021] The fuel discharge member may be disposed so that the fueldischarge outlets of the main body open the perpendicular orapproximately perpendicular to the air flow passage. In this case, thefuel is discharged by a strong penetration force through the air flow inwhich the generation of swirls is suppressed at downstream side of thefuel discharge member.

[0022] In the fuel discharge member, the trailing edge of the main bodymay be inclined so that the base end of the trailing edge extendsfurther downstream from the tip end of the trailing edge with respect tothe air flowwhich is to be formed in the air flow passage. Thereby, theair flows in a radially outward direction along the trailing edge, sothat the generation of a second flow, which may cause the generation ofswirls, is suppressed. In this case, the trailing edge may be formedwith a detachable inclined member. Thus, the fuel discharge member ofwhich the trailing edge is inclined can be easily manufactured.

[0023] In the fuel discharge member, the fuel discharge outlets may bedisposed axially in a plurality of lines at radially staggered positionson both sides of the main body. Thereby, the fuel flow discharged fromthe respective fuel discharge outlets can be made uniform.

[0024] In the fuel discharge member, the fuel discharge outlets may opentoward the downstream direction so as to discharge the fuel in thedownstream direction of the fuel discharge member with respect to theair flow. By the use of this fuel discharge member, it is possible tomake the concentration distribution of the fuel uniform.

[0025] The cross-sectional shape of the fuel discharge member may be anelliptical shape, a flat oval shape, or an annular shape. The trailingedge may be formed with a protruding portion at the downstream side withrespect to the air flow.

[0026] A burner according to the present invention includes a fuelsupply conduit in which a fuel passage is formed so as to communicatewith a fuel supply source; the fuel discharge member described above;and swirlers which are fixed on the fuel supply conduit so as to rotatean air flow or a premixed gas flow containing air and fuel.

[0027] A plurality of fuel discharge members may be arranged axially ina plurality of lines on the fuel supply conduit. Thereby, the number offuel discharge outlets can be increased without decreasing the effectivearea of the air flow passage.

[0028] The fuel discharge members may be disposed so that the fueldischarge members are circumferentially displaced in relation to oneanother. In this case, the circumferential concentration distribution ofthe fuel can be made uniform.

[0029] The swirlers may be disposed downstream of the fuel dischargemember with respect to the air flow. The swirler and the fuel dischargemember may be arranged circumferentially in the same line. In this case,since the turbulence of the flow velocities caused by the fuel dischargemember interacts with the turbulence of the flow velocities caused bythe swirler, the turbulence of the flow velocities caused by the fueldischarge member downstream thereof can be prevented.

[0030] Alternatively, the swirlers may be disposed so that the swirlerand the fuel discharge member are circumferentially staggered withrespect to each other. In this case, since the turbulence of the flowvelocities are generated respectively downstream of the fuel dischargemember and the swirler, the turbulence of the flow velocities are madeapproximately uniform downstream of the swirler.

[0031] The fuel supply conduit may further comprise a liquid fuelpassage which communicates with a liquid fuel supply source, and fueldischarge holes which communicate with the liquid fuel passagesubstantially at the tip end portions of the fuel supply conduit.

[0032] This burner suppresses the generation of swirls downstream of thefuel discharge member, so that the concentration distribution of thefuel can be made uniform. Thus, since the amount of fuel burned at ahigh fuel/air ratio, which causes an increase in the amount of NOxexhaust, is reduced, the amount of NOx exhaust can be reduced.

[0033] A premixing nozzle of the combustor according to the presentinvention has a pilot burner which is disposed on the central axis ofthe premixing nozzle, and also has the burners described above which aredisposed as main burners surrounding the pilot burner.

[0034] Since the premixing nozzle of the combustor is provided with theburners which suppress the generation of swirls downstream of the fueldischarge member, it is possible to make the concentration distributionof the fuel uniform. Therefore, the amount of fuel burned at a highfuel/air ratio, which causes an increase in the amount of NOx, exhaustis reduced, and the amount of NOx exhaust is reduced.

[0035] A combustor of the present invention has the premixing nozzledescribed above, and a cylinder which holds the premixing nozzletherein.

[0036] Since this combustor includes the premixing nozzle which cansuppress the generation of swirls downstream of the fuel dischargemember, it is possible to make the concentration distribution of thefuel uniform. Thereby, the amount of fuel burned at a high fuel/airratio, which causes an increase in the amount of NOx exhaust, isreduced, and the amount of NOx exhaust is reduced.

[0037] A gas turbine of the present invention comprises a compressorwhich compresses air to generate a high-pressure gas; the combustordescribed above, which is connected to the compressor so as to besupplied with the high-pressure gas from the compressor, and which heatsthe high-pressure gas to generate a high-temperature and high-pressuregas; and a turbine which is connected to the combustor so as to besupplied with the high-temperature and high-pressure gas from thecombustor, and which rotates an out shaft by expanding thehigh-temperature and high-pressure gas to generate a shaft output.

[0038] Since this gas turbine includes the combustor which can suppressthe generation of swirls downstream of the fuel discharge member, it ispossible to make the concentration distribution of the fuel uniform.Thereby, the amount of fuel burned at a high fuel/air ratio, whichcauses an increase in the amount of NOx exhaust, is reduced, and theamount of NOx exhaust is reduced.

[0039] A jet engine of this present invention comprises a compressorwhich compresses air to generate a high-pressure gas, the combustordescribed above, which is connected to the compressor so as to besupplied with the high-pressure gas from the compressor, and which heatsthe high-pressure gas to generate a high-temperature and high-pressuregas, and the turbine which is connected to the combustor so as to besupplied with the high-temperature and high-pressure gas from thecombustor.

[0040] Since this jet engine includes the combustor which can suppressthe generation of swirls downstream of the fuel discharge member, it ispossible to make the concentration distribution of the fuel uniform.Thereby, the amount of fuel burned at a high fuel/air ratio, whichcauses an increase in the amount of NOx exhaust, is reduced, and theamount of NOx exhaust is reduced.

BRIEF DESCRIPTION OF DRAWINGS

[0041]FIGS. 1A to 1C show a burner comprising a fuel discharge member ofa first embodiment according to the present invention: FIG. I A is across-sectional view of a key portion of the burner; FIG. 1B is across-sectional view of the fuel discharge member taken along the lineA-A of FIG. 1A; and FIG. 1C is a cross-sectional view of the burnertaken along the line B-B of FIG. 1A.

[0042]FIG. 2 is a graph which shows the relationship between the flowpassage block ratio of a fuel discharge member and the NOxconcentration.

[0043]FIGS. 3A to 3E show respective modified cross-sectional shapes ofthe fuel discharge member of a first embodiment according to the presentinvention: FIG. 3A is a cross-sectional view of a first modification;FIG. 3B is a cross-sectional view of a second modification; FIG. 3C is across-sectional view of a third modification; FIG. 3D is across-sectional view of a fourth modification, and FIG. 3E is across-sectional view of a fifth modification.

[0044]FIG. 4A is a cross-sectional view of a key portion of a burnercomprising a fuel discharge member of a second embodiment according tothe present invention. FIG. 4B is a cross-sectional view of the fueldischarge member, which is taken along the line C-C of FIG. 4A.

[0045]FIGS. 5A and 5B show a modified fuel discharge member according tothe present invention: FIG. 5A is a cross-sectional view, and FIG. 5B isa cross-sectional view taken along the line D-D of FIG. 5A.

[0046]FIG. 6 is a schematic representation which illustrates the actionof the second embodiment shown in FIG. 4A.

[0047]FIGS. 7A and 7B show a fuel discharge member of a third embodimentaccording to the present invention: FIG. 7A is a cross-sectional view ofa key portion of the fuel discharge member, and FIG. 7B is across-sectional view taken along the line E-E of FIG. 7A.

[0048]FIGS. 8A and 8B show the relationship between the fuel dischargemember and swirlers of a fourth embodiment according to the presentinvention: FIG. 8A is a schematic representation which illustrates therelationship between the fuel discharge member and the main swirlers,wherein the fuel discharge member and the main swirlers are staggered;and FIG. 8B is a schematic representation which illustrates therelationship between the fuel discharge member and the main swirlers,wherein the fuel discharge member and one main swirler are arranged inthe same line.

[0049]FIG. 9 is a cross-sectional view which shows a burner according toa fifth embodiment of the present invention.

[0050] FIGS. lOA and lOB show a combustor including a fuel dischargemember of the present invention: FIG. 10A is a cross-sectional view of akey portion of the combustor, and FIG. 10B is a cross-sectional view ofFIG. 10A.

[0051]FIG. 11 is a cross-sectional view which shows a combustoraccording to the prior art.

DETAILED DESCRIPTION OF THE INVENTION

[0052] In the following, embodiments according to the present inventionwill be explained with reference to the drawings.

[0053] First Embodiment

[0054] A gas turbine expands a high-temperature and high-pressure gas inthe turbine and rotates the main shaft to generate a shaft output whichis used as a driving force for an electric power generator and the like.A jet engine expands the high-temperature and high-pressure gas in theturbine and rotates the main shaft to exert kinetic energy of ahigh-velocity jet (exhaust), discharged from an outlet of the turbine,as a propelling force of an aircraft.

[0055] The main components of the gas turbine and the jet engine are acompressor, a combustor, and a turbine.

[0056] The compressor compresses a gas, that is air, which is introducedfrom an inlet thereof, as a working fluid in order to supply ahigh-pressure gas to the combustor that is connected to the outlet ofthe compressor. This compressor used is an axial compressor which isconnected to the turbine through the main shaft. In the combustor, thehigh-pressure gas is burned to generate a high-temperature andhigh-pressure. Then, the high-temperature and high-pressure gas issupplied to the turbine.

[0057] In the following, the combustor according to a first embodimentis described with reference to FIGS. 10A and 10B.

[0058] A combustor 10 is equipped with a premixing nozzle 12 along acentral axis of an internal cylinder 11. The internal cylinder 11 is acircular cylinder of which both ends open. The premixing nozzle 12includes a pilot burner 13 and a plurality of main burners 14. The pilotburner 13 is provided at the central position which coincides with thecentral axis of the premixing nozzle 12. The plurality of main burners14 are disposed at even intervals so as to surround the pilot burner 13.Therefore, the central axis of the pilot burner 13 is the central axisof the internal cylinder 11. In FIG. 10B, eight main burners 14 aredisposed so as to surround the pilot burner 13, wherein the main burners14 each have the same form.

[0059] The pilot burner 13 of the premixing nozzle 12 includes a pilotfuel tube 15 and pilot swirlers 16. The pilot fuel tube 15 is a circularcylinder of which one end is connected to a fuel supply source which isnot shown, so that pilot fuel is supplied to the pilot fuel tube 15 fromthe fuel supply source. At the other end of the pilot fuel tube 15, apilot fuel nozzle 15 a is formed so as to open toward a combustionchamber 10 a of the combustor 10 which is formed on the internalcylinder 11. Thus, the pilot fuel is supplied to the combustion chamber10 a from the pilot fuel nozzle 15 a. The pilot swirlers 16 have atwisted shape, and are fixed on the pilot fuel tube 15 at even intervalsin the circumferential direction. In FIG. 10B, the pilot swirlers 16 aredisposed on the pilot fuel tube 15 at intervals of 45° in thecircumferential direction. The pilot swirlers 16 give a swirling motionto the air flow (shown by an arrow) which passes through the pilotswirlers 16. Thereby, the air flow is emitted to the surroundings of thepilot fuel nozzle 15 a.

[0060] The pilot fuel supplied from the pilot fuel nozzle 15 a burns theswirled flow of air as combustion gas to generate flames in thecombustion chamber 10 a. Thus, flames generated by the pilot burners 13are used to generate flames at the main burner 14.

[0061] The main burner 14 of the premixing nozzle 12 includes a fuelsupply conduit 17, fuel discharge members 20, and swirlers 18. The fuelsupply conduit 17 is a circular cylinder in which a fuel passage isformed. One end of the fuel supply conduit 17 is connected to a fuelsupply source, which is not shown, in order to supply main fuel to thefuel supply conduit 17. The other end of the fuel supply conduit 17 isclosed. The fuel discharge members 20 are fixed on the fuel supplyconduit 17 at even intervals in the circumferential direction. The fueldischarge member 20 includes a main body having an internal space whichcommunicates with the fuel supply conduit 17, and fuel discharge outlets21 which communicate with the internal space, so as to discharge themain fuel into the air flow. The swirlers 18 have a twisted shape, andare fixed on the fuel supply conduit 17 at even intervals in thecircumferential direction. In FIG. 10B, the swirlers 18 are disposed onthe fuel supply conduit 17 at intervals of 45 in the circumferentialdirection. The swirlers 18 are disposed downstream of the fuel dischargemembers 20. The swirlers 18 give a swirling motion to the air flowpassing at the peripheral portion of the fuel supply conduit 17. In FIG.10B, eight main burners 14 contact each other and surround the pilotburner 13.

[0062] Thus, the main burners 14 discharge the main fuel gas, which isintroduced through the fuel supply conduit 17 to a fuel discharge outlet21, into the air flow from the fuel discharge outlet 21. Thereby, thefuel gas and the air are premixed, so that a premixed gas is generated.When the premixed gas passes through the swirlers 18, the premixed gasis swirled by the swirlers 18, and subsequently emitted to thecombustion chamber 10 a of the combustor 10. The premixed gas is led tothe surroundings of the pilot burner 13 from the eight main burners 14in the combustion chamber lOa. The premixed gas is ignited by the flamesgenerated by the pilot burner 13 described above, so that ahigh-temperature gas is generated. The generated gas is emitted from anaperture which is disposed at one end of the internal cylinder 11.

[0063] An external cylinder 19 is disposed on the outer side of theinternal cylinder 11. The external cylinder 19 is a circular cylinder ofwhich one end is opened. At the other end of the external cylinder 19,an introductory passage of the air flow is formed so as to reverse theair flow direction.

[0064] In the following, the burner used as the main burner 14 accordingto the first embodiment will be explained in further detail.

[0065]FIG. 1A shows the burner including the fuel supply conduit 17, thefuel discharge members 20, and the swirlers 18. The fuel dischargemember 20 includes the main burner 14, the fuel supply conduit 17, theswirlers 18, and the fuel discharge outlets 21.

[0066] As shown in FIG. 1A, the fuel discharge members 20 are fixed onthe fuel supply conduit 17 and radially protrude into the air flowpassage (shown by an arrow). The fuel discharge member 20 includes amain body 23 having an internal space 22, fuel discharge outlets 21, anda trailing edge 23 a. The tip end of the main body 23 is closed, and thebase end of the main body 23 communicates with the fuel passage in thefuel supply conduit 17 through the internal space 22. The internal space22 is formed so as to communicate with the fuel passage in the fuelsupply conduit 17 at the base end of the internal space 22. In FIG. 1A,two fuel discharge outlets 21 are centrally aligned at opposite sides ofthe main body 23, respectively. The fuel discharge outlets 21 opentoward a perpendicular or almost perpendicular direction to the air flowpassage. The fuel discharge outlets 21 are formed so as to communicatewith the internal space 22. However, the number of fuel dischargeoutlets 21 formed in the main body 23 is not limited to two, and therelationship between the fuel discharge outlets 21 is also not limitedsuch that they are aligned.

[0067] In FIG. 1B, the main body 23 used is a flat tube of which thecross-sectional shape is a flat oval shape. The flat oval shape has twoopposite linear portions disposed parallel to each other and both tipends of the opposite linear portions are connected to each other formingsemicircular portions, as shown in FIG. 1B. The thickness of the mainbody 23 in a direction perpendicular to the air flow passage is set tobe no more than 5 mm or to be thin enough such that the flow passageblock ratio thereof (the ratio of the cross-sectional area, wherein thetrailing edge 23 a of the fuel discharge member 23 occupies the air flowpassage, to the total cross-sectional area of the air flow passage) isno more than 10%. As a result, the thickness of the trailing edge 23 aof the main body 23 becomes thin.

[0068] In FIG. 1C, four fuel discharge members 20 are disposed atintervals of 90° in the circumferential direction. The swirlers 18 aredisposed at intervals of 45° in the circumferential direction downstreamof the fuel discharge members 20, with respect to the flow of the air.The swirlers 18 have a twisted shape.

[0069] As described above, since the thickness t of the trailing edge 23a of the main body 23 is set to be no more than 5 mm or to be thinenough such that the flow passage block ratio thereof is no more than10%, an interrupted effective area of the air flow passage, wherein theair flow is interrupted by the fuel discharge member 20 fixed on thefuel supply conduit, is decreased, so that the flow of the premixed gasis made uniform. Thus, a negative pressure area, caused by theinterruption of the flow of the premixed gas by the fuel dischargemember 20 and formed downstream of the trailing edge 23 a, is decreased,so that the generation of swirls caused by the negative pressure area,wherein the air flow is entrained, is reduced.

[0070] Thereby, the turbulence of the velocity distribution of the airflow is decreased at the downstream side of the fuel discharge member20. Thus, since the penetration force of the fuel gas discharged fromthe fuel discharge outlet 21 can be maintained approximately constantly,the concentration distribution of the fuel gas in the premixed gas canbe constantly maintained in spite of the quality or the quantity of thefuel gas in the premixed gas.

[0071] Since four fuel discharge members 20 are disposed at intervals of90° in the circumferential direction and the plurality of fuel dischargeoutlets 21 are disposed respectively on both sides of the fuel dischargemembers 20, the circumferential concentration distribution of the fuelgas is made uniform. Moreover, since two fuel discharge outlets 21 aredisposed radially in a line on the opposite sides of the fuel dischargemember 20, the radial concentration distribution of the fuel gas is madeuniform. The number of fuel discharge members 20 and the arrangement ofthe fuel discharge members 20 may be suitably decided.

[0072] In FIG. 2, experimental results show the relationship between theflow passage block ratio of the fuel discharge members 20 and theconcentration of NOx exhausted. When the flow passage block ratio of thefuel discharge members 20 is increased, the concentration of NOxexhausted is also increased.

[0073] In the United States, the concentration of NOx exhausted isrestricted to be no greater than 25 ppm. According to the experimentalresults shown in FIG. 2, the flow passage block ratio of the fueldischarge members 20 may be set to no more than 10% to satisfy therestriction of the concentration described above. When the flow passageblock ratio of the fuel discharge members 20 is set to 7%, theconcentration of NOx exhausted is 9 ppm.

[0074] The cross-sectional shape of the main body 23 described above maybe another modified shape other than the flat oval shape shown in FIG.1B.

[0075] In a first modification shown in FIG. 3A, a flat tube, whereinthe cross-sectional shape is a flat oval shape, is used, and two fueldischarge outlets 21 are disposed on both sides and staggered withrespect to each other in the direction of the air flow, that is, in theaxial direction of the fuel supply conduit 17. Thus, interaction betweenthe fuel discharge outlets 21 can be reduced, so that the fuel gas isconstantly supplied.

[0076] In a second modification shown in FIG. 3B, a flat tube, whereinthe cross-sectional shape is an elliptical shape, is used, and theopposite sides in which the fuel discharge outlets 21 are disposed, arecurved.

[0077] In a third modification shown in FIG. 3C, the trailing edge 23 ais formed with a protruding portion 24 disposed on the end of thetrailing edge side of the first modification. In this case, theprotruding portion 24 may be formed into a semicircle of which theradius R is small enough so that the thickness t of the trailing edge 23a is no more than 5 mm or the flow passage block ratio of the fueldischarge member is no more than 10% with respect to the cross-sectionalarea of the air flow passage in which the fuel discharge member 20 is tobe placed. Thereby, the internal space 22 of the main body 23 has alarge cross-sectional shape, so that a large flow of the fuel gas can beeasily maintained. Moreover, the generation of swirls at the downstreamside is prevented, so that the fuel concentration distribution can bemade uniform.

[0078] In a fourth modification shown in FIG. 3D, protruding portions 24and 25 are disposed at opposite sides to form the trailing edge 23 a anda leading edge of the fuel discharge member 20 according to the secondmodification, and thereby, the generation of swirls downstream of thefuel discharge member 20 is satisfactorily prevented. These protrudingportions 24 and 25 may be disposed in another type of fuel dischargemember of which the cross-sectional shape is a flat oval shape or acircular shape, for example.

[0079] In a fifth modification shown in FIG. 3E, the trailing edge 23 ais thin enough such that the thickness of the trailing edge 23 a is nomore than 5 mm or the flow passage block ratio of the fuel dischargemember 20 is no more than 10% (R <2.5 mm). The cross-sectional shape ofthe main body 23 is a wing shape, and the cross-sectional shape of theinternal space 22 is an elliptical shape. In this case, the generationof swirls is suppressed as described above.

[0080] The cross-sectional shape of the internal space 22 is not limitedto an elliptical shape, and may be a flat oval shape or an annularshape.

[0081] Second Embodiment

[0082] In the following, a burner including a fuel supply conduit 17, afuel discharge member 30, and swirlers 18 of the second embodiment willbe explained with reference to FIGS. 4A. and 4B. In this case, the samemembers as those of the first embodiment are indicated by the samereference numbers, and descriptions of the same members are omitted.

[0083] In FIG. 4A, fuel discharge members 30 and swirlers 18 are fixedon the fuel supply conduit 17.

[0084] The fuel discharge member 30 including a main body 33 having fueldischarge outlets 31, an internal space 32, and a trailing edge 33 a isshown. In this embodiment, the trailing edge 33 a is inclined so thatthe base end of the trailing edge 33 a extends further downstream fromthe tip end of the trailing edge 33 a with respect to the air flow whichis to be formed in the air flow passage. That is, the shape of the fueldischarge member 30 as viewed from the side is a tail assembly shape.

[0085] The internal space 32 communicates with the fuel passage in thefuel supply conduit 17 at the base end of the internal space 32. In themain body 33, the fuel discharge outlets 31 open toward a directionperpendicular to the air flow passage and communicate with the internalspace 32. In FIG. 4A, on the opposite sides of the main body 33, twofuel discharge outlets 31 are arranged along an angular line withrespect to the air flow and are staggered axially with respect to eachother. Thus, four fuel discharge outlets 31 are disposed on therespective main bodies 33 so as to be axially displaced in relation toone another.

[0086] In this case, the main body 33 used is a flat tube wherein thecross-sectional shape is a flat oval shape of which both opposite sidesare parallel to each other and both tip ends are connected to each otherforming a curve, as shown in FIG. 4B. The thickness t of the main body33 in a direction perpendicular to the air flow passage is set to be nomore than 5 mm or to be thin enough such that the flow passage blockratio of the fuel discharge member is no more than 10% with respect tothe cross-sectional area of the air flow passage in which the fueldischarge member 20 is to be placed. In this case, the thickness of thetrailing edge 33 a of the main body 33 becomes thin.

[0087] In FIG. 4A, four fuel discharge members 30 are disposed atintervals of 90° in the circumferential direction and protrude radially,and swirlers 18 are disposed at intervals of 45° in the circumferentialdirection downstream of the fuel discharge members 30 with respect tothe air flow.

[0088] The cross-sectional shape of the main body 33 is not limited tothe flat oval shape described above, and may be the cross-sectionalshapes shown in FIGS. 3A to 3E, respectively.

[0089] As shown in FIG. 5A, the trailing edge 33 a may be formed with adetachable inclined member 34 of which the lateral shape is a triangle,so that the trailing edge 33 a is inclined. This construction makes iteasy to manufacture the fuel discharge member 30 of which the trailingedge 33 a is inclined.

[0090] In the following, the effects of the fuel discharge member 30, ofwhich trailing edge 33 a is inclined, will be explained with referenceto FIG. 6.

[0091] In general, a negative pressure area is formed downstream of thefuel discharge member 33, and thereby, the air flow is swirled. Incontrast, when the trailing edge 33 a of the fuel discharge member 30 isinclined as shown in FIG. 6, the air flows from the base end of the fueldischarge member 30 along the incline of the trailing edge 33 a, so thatthe air flow is prevented from being swirled. Thus, the concentrationdistribution of the fuel gas can be made uniform.

[0092] Since the fuel discharge member 30 is a flat tube, the fueldischarge outlets 31 are staggered axially. That is, one of the fueldischarge outlets 31, positioned axially upstream with respect to theair flow, is disposed near the tip end of the fuel discharge member 30.The other of the fuel discharge outlets 31, positioned axiallydownstream with respect to the air flow, is arranged near the base endof the fuel discharge member 30. The fuel gas can be uniformlydischarged from both fuel discharge outlets 31 which are axiallystaggered. Therefore, even if the number of fuel discharge outlets 31 isincreased, the radial penetration force is made uniform. Moreover, theradial concentration distribution of the fuel gas can be made uniform byinclining the trailing edge 33 a as described above. The circumferentialconcentration distribution can be easily made uniform by increasing thenumber of fuel discharge members 30 and fuel discharge outlets 31.

[0093] Third Embodiment

[0094] In the third embodiment, the fuel discharge members 30 aredisposed on the fuel supply conduit 17 in a plurality of lines along theaxial direction of the fuel supply conduit 17 (along the flow directionof the air). In FIG. 7A, the fuel discharge members 30 are axiallyarranged in two lines.

[0095] In this case, a fuel discharge member 30A located upstream and afuel discharge member 30B located downstream may be arranged at the sameposition circumferentially and protrude radially. Alternatively, thefuel discharge members 30A and 30B may be staggered circumferentially asshown in FIG. 7B.

[0096] When the plurality of fuel discharge members 30 are respectivelyarranged at the same positions circumferentially as described above, theeffective area of the air flow passage in which the plurality of fueldischarge members 30 are to be placed hardly changes compared to theeffective area in which only one fuel discharge member 30 is to beplaced. Therefore, the number of fuel discharge outlets 31 to bedisposed can be increased while maintaining the effective area of theair flow passage, and the circumferential concentration distribution ofthe fuel gas can be made uniform.

[0097] When the plurality of fuel discharge members 30 are staggeredcircumferentially, the interval which circumferentially separates thefuel discharge outlets 31 from each other becomes small, in accordancewith the increase in the number of fuel discharge outlets 31. Therefore,the circumferential concentration distribution of the fuel gas can bemade more uniform.

[0098] Fourth Embodiment

[0099] In the fourth embodiment shown in FIGS. 8A and 8B, therelationship between the fuel discharge member 30 and the swirlers 18 isdescribed.

[0100] In FIG. 8A, the fuel discharge member 30 and the swirlers 18 arestaggered circumferentially. That is, the fuel discharge member 30 isdisposed upstream of a position which is located between the adjacentswirlers 18. In this case, the intensity of the turbulence of flowvelocity v′ is enlarged in accordance with the proximity to the fueldischarge member 30, as shown in FIG. 8A. The fuel gas is engulfed inswirls generated at downstream of the fuel discharge member 30, so thatthe fuel gas becomes concentrated. In contrast, the intensity of theturbulence of flow velocity v″ is generated downstream of the swirlers18, as shown in FIG. 8A. The turbulence of flow velocity v″ interactswith the turbulence of flow velocity v′, so that the distribution of theturbulence of the flow velocity becomes uniform at downstream of theswirlers 18. Then, a premixed gas, wherein the fuel gas is dischargedinto the air, is mixed by this uniform turbulence of the flow velocity,so that the concentration distribution of the fuel gas becomes uniform.

[0101] In FIG. 8B, the fuel discharge member 30 and one of the swirlers18 are aligned circumferentially. That is, the fuel discharge member 30is located circumferentially upstream of the swirlers 18. In this case,positions of the turbulence of flow velocity v′ caused by the fueldischarge member 30 and the turbulence of flow velocity v″ caused by theswirlers 18 are circumferentially consistent with each other, so thateffects caused by the fuel discharge member 30 at the downstream sidecan be suppressed. That is, the turbulence of the flow velocity causedby the fuel discharge member 30 is substantially negligible.

[0102] Fifth Embodiment

[0103] In FIG. 9, a burner 14A including a fuel supply conduit 40, fueldischarge members 30, and swirlers 18 according to the fifth embodimentis shown. In the fuel supply conduit 40, a fuel passage (not shown), aliquid fuel passage (not shown), and fuel discharge outlets 41 areformed. The fuel passage is formed so as to communicate with a fuel gassupply source to supply the fuel gas to the fuel discharge members 30.The liquid fuel passage is formed so as to communicate with a liquidfuel supply source to supply liquid fuel to the fuel discharge outlets41. The fuel discharge outlets 41 are formed so as to communicate withthe liquid fuel passage substantially at the tip end portions of thefuel supply conduit 40. The fuel discharge outlets 41 open toward thedownstream direction of the swirlers 18 with respect to the air flow.

[0104] By the use of this burner 14A, premixed gas, wherein theconcentration of the fuel gas is uniform, can be formed in the samemanner as described above.

[0105] As described above, by using the fuel discharge member 20 or 30,the concentration distribution of the fuel gas in the premixed gas,wherein air and fuel gas are mixed, can be made circumferentially andradially uniform, so that the area, wherein the concentration of thefuel gas is high, that is, the fuel/air ratio is over 1, can be reduced.

[0106] When the concentration distribution of the fuel gas is madeuniform, even if the temperature for the combustion is raised to near1600° C., the amount of NOx generated during the combustion can bereduced. Thus, by using a burner having a fuel discharge member, apremixing nozzle having a burner, and a combustor having a premixingnozzle, the total amount of NOx generated can be reduced. Moreover, agas turbine and a jet engine, which include a burner, a premixingnozzle, and a combustor, can reduce the amount of NOx generated, even ifthe temperature for the combustion is raised to operate with higheffectiveness. Particularly, when the trailing edge of the fueldischarge member 20 or 30 is set to be thin enough such that thethickness thereof is no more than 5 mm or the flow passage block ratioof the fuel discharge member is no more than 10% with respect to thecross-sectional area of the air flow passage in which the fuel dischargemember is to be placed, the generation of NOx can be considerablyreduced.

[0107] Although the fuel discharge outlets 21 and 31 are respectivelydisposed in the fuel discharge members 20 and 30 perpendicular orapproximately perpendicular to the air flow passage, the fuel dischargeoutlets according to the present invention may be disposed downstream ofthe fuel discharge members with respect to the direction of the airflow.

[0108] Although the swirlers 18 are preferably disposed downstream ofthe fuel discharge members 20 or 30, the swirlers may be disposedupstream of the fuel discharge members.

[0109] Although the fuel discharge members are disposed in the mainburner of the premixing nozzle in the respective embodiments describedabove, the fuel discharge members may be disposed in a pilot burner.

[0110] Although the combustor 10, the premixing nozzle 12, the mainburner 14, the gas turbine, and the jet engine include the fueldischarge member according to the present invention, configurations ofthe combustor 10, the premixing nozzle 12, the main burner 14, the gasturbine, and the jet engine are not limited to the configurationsdescribed in the respective embodiments. That is, the number of pilotburners 13 and main burners 14 disposed in the premixing nozzle 12 orthe number of fuel discharge members protruding from the main burner 14may be suitably selected, for example.

[0111] It is understood, by those skilled in the art, that the foregoingdescription is a preferred embodiment of the disclosed configurationsand that various changes and modifications may be made to the inventionwithout departing from the spirit and scope thereof.

[0112] The following effects can be obtained by the present invention.

[0113] By using the fuel discharge member of which the thickness at thetrailing edge is no more than 5 mm or the flow passage block ratio ofthe fuel discharge member is no more than 10% with respect to thecross-sectional area of the air flow passage in which the fuel dischargemember is to be placed, the generation of swirls downstream of the fueldischarge member is reduced, so that the concentration distribution ofthe premixed gas including air and fuel is made uniform. Therefore, thetotal amount of NOx exhaust can be reduced, even if the temperature forthe combustion is raised.

[0114] By using a flat tube as the fuel discharge member, the generationof swirls downstream of the fuel discharge member is reduced, so thatthe concentration distribution of the premixed gas including air andfuel is made uniform. Moreover, the number of fuel discharge outlets canbe increased, and the fuel discharge outlets can be suitably disposed.Thereby, the concentration distribution can be made radially andcircumferentially uniform.

[0115] By using the burner, the premixing nozzle, and the combustor, theconcentration distribution of the premixed gas including air and fuel ismade uniform. Therefore, the total amount of NOx exhaust can be reduced,even if the temperature for the combustion is raised.

[0116] By using the gas turbine or the jet engine, since theconcentration distribution of the premixed gas is uniformly maintained,the total amount of NOx exhaust can be reduced, even if the temperaturefor the combustion is raised. Thus, highly effective operation and thereduction of the amount of NOx exhaust can be achieved at the same time.

1. A fuel discharge member to be fixed on a fuel supply conduit,comprising: a main body having an internal space which communicates witha fuel passage in the fuel supply conduit; fuel discharge outlets whichcommunicates with the internal space; and a trailing edge, wherein thethickness of the trailing edge is no more than 5 mm, or a flow passageblock ratio of the fuel discharge member is no more than 10% withrespect to the cross-sectional area of the air flow passage in which thefuel discharge member is to be placed.
 2. A fuel discharge memberaccording to claim 1, wherein the fuel discharge outlets open toward asubstantially perpendicular direction to the air flow passage.
 3. A fueldischarge member according to claim 1, wherein the trailing edge of themain body is inclined so that the base end of the trailing edge extendsfurther downstream from the tip end of the trailing edge with respect tothe air flow which is to be formed in the air flow passage.
 4. A fueldischarge member according to claim 3, further comprising a detachableinclined member, which forms the trailing edge.
 5. A fuel dischargemember according to claim 1, wherein the fuel discharge outlets areaxially arranged in a plurality of lines and radially staggered on themain body.
 6. A fuel discharge member according to claim 1, wherein thefuel discharge outlets open toward the downstream direction with respectto the air flow.
 7. A fuel discharge member according to claim 1,wherein the cross-sectional shape of the main body is a flat oval shape,an elliptical shape, or an annular shape, and the trailing edge isformed with a protruding portion at the downstream side with respect tothe air flow.
 8. A fuel discharge member to be fixed on a fuel supplyconduit, comprising: a main body having an internal space whichcommunicates with a fuel passage in the fuel supply conduit; fueldischarge outlets which communicate with the internal space; and atrailing edge, wherein the main body is a flat tube.
 9. A fuel dischargemember according to claim 8, wherein the fuel discharge outlets opentoward a substantially perpendicular direction to the air flow passage.10. A fuel discharge member according to claim 8, wherein the trailingedge of the main body is inclined so that the base end of the trailingedge extends further downstream from the tip end of the trailing edgewith respect to the air flow which is to be formed in the air flowpassage.
 11. A fuel discharge member according to claim 10, furthercomprising a detachable inclined member, which forms the trailing edge.12. A fuel discharge member according to claim 8, wherein the fueldischarge outlets are axially arranged in a plurality of lines andradially staggered on the main body.
 13. A fuel discharge memberaccording to claim 8, wherein the fuel discharge outlets open toward thedownstream direction with respect to the air flow.
 14. A fuel dischargemember according to claim 8, wherein the flat tube has a cross-sectionalshape of a flat oval shape or an elliptical shape.
 15. A burnercomprising: a fuel supply conduit in which a fuel passage is formedwhich communicates with a fuel supply source; a fuel discharge memberaccording to claim 1; and swirlers which are fixed on the fuel supplyconduit so as to rotate an air flow or a premixed gas flow containingair and fuel.
 16. A burner according to claim 15, wherein the fueldischarge members are arranged axially in a plurality of lines.
 17. Aburner according to claim 16, wherein the fuel discharge members are sodisposed so as to be circumferentially displaced with respect to eachother.
 18. A burner according to claim 15, wherein the swirlers aredisposed downstream of the fuel discharge members with respect to theair flow, and are circumferentially aligned with the fuel dischargemembers.
 19. A burner according to claim 15, wherein the swirlers aredisposed downstream of the fuel discharge members with respect to theair flow, and the swirlers and the fuel discharge members arecircumferentially staggered with respect to each other.
 20. A burneraccording to claim 15, wherein the fuel supply conduit furthercomprises: a liquid fuel passage which communicates with a liquid fuelsupply source; and fuel discharge outlets which communicate with theliquid fuel passage substantially at the tip end portions of the fuelsupply conduit.
 21. A burner comprising: a fuel supply conduit in whicha fuel passage is formed which communicates with a fuel supply source; afuel discharge member according to claim 8; and swirlers which are fixedon the fuel supply conduit so as to rotate an air flow or a premixed gasflow containing a air and fuel.
 22. A burner according to claim 21,wherein the fuel discharge members are arranged axially in a pluralityof lines.
 23. A burner according to claim 22, wherein the fuel dischargemembers are so disposed so as to circumferentially displaced withrespect to each other.
 24. A burner according to claim 21, wherein theswirlers are disposed downstream of the fuel discharge members withrespect to the air flow, and are circumferentially aligned with the fueldischarge members.
 25. A burner according to claim 21, wherein theswirlers are disposed at downstream of the fuel discharge members withrespect to the air flow, and the swirlers and the fuel discharge membersare circumferentially staggered with respect to each other.
 26. A burneraccording to claim 21, wherein the fuel supply conduit furthercomprises: a liquid fuel passage which communicates with a liquid fuelsupply source; and fuel discharge outlets which communicate with theliquid fuel passage substantially at the tip end portions of the fuelsupply conduit.
 27. A premixing nozzle of a combustor, comprising: apilot burner disposed on a central axis of the premixing nozzle; and aplurality of burners according to claim 15 or 20, which are disposed asmain burners surrounding the pilot burner.
 28. A combustor comprising: apremixing nozzle according to claim 27; and a cylinder which holds thepremixing nozzle therein.
 29. A gas turbine comprising: a compressorwhich compresses an air to generate a high-pressure gas; a combustoraccording to claim 28, which is connected to the compressor so as to besupplied with the high-pressure gas from the compressor, and which heatsthe high-pressure gas to generate a high-temperature and high-pressuregas; and a turbine which is connected to the combustor so as to besupplied with the high-temperature and high-pressure gas from thecombustor, and which rotates an out shaft by expanding thehigh-temperature and high-pressure gas to generate a shaft output.
 30. Ajet engine comprising: a compressor which compresses an air to generatea high-pressure gas; the combustor according to claim 28, which isconnected to the compressor so as to be supplied with the high-pressuregas from the compressor, and which heats the high-pressure gas togenerate a high-temperature and high-pressure gas; and a turbine whichis connected to the combustor so as to be supplied with thehigh-temperature and high-pressure gas from the combustor.